It comes just weeks before new strict rules, which are set to limit the use of cookies in order to control online privacy, come into effect.

On May 26, the UK's Information Commissioner's Office (ICO) will impose an EU directive - also known as the "Cookie Directive" - designed to protect internet users' privacy.

The law says sites must provide "clear and comprehensive" information about the use of cookies and trackers.

When the legislation comes in to place, website managers must tell people that the cookies are there, explain what they are doing and, most importantly, get people's consent to store a cookie on their computer.

Truste found that most companies that took part in the study had published a privacy policy but only 16% had a summary section that was easy to understand.

It also said the average UK website privacy policy is more than twice as long as the typical Queen's Speech and over half the length of the Magna Carta.

Chris Babel, chief executive of Truste, said: "Clearly more work needs to be done to deliver shorter, more accessible privacy notices that can be easily understood by consumers so that they can make informed choices around their personal information."